1. Field of the Invention
The present invention relates to a magnetic tape, a servo pattern recording apparatus for the magnetic tape, a magnetic tape apparatus such as a linear magnetic tape apparatus, a method of producing the magnetic tape, and a recording method of the magnetic tape.
2. Description of the Related Art
Track-following servo control of the related art involves, for example, providing a longitudinal servo track previously recorded between longitudinal data track groups, the servo track being parallel to the data track groups, so that the servo track can be read by one or a plurality of servo heads, adjusting a position of the head or tape in a tape width direction by a subsidiary track-following servo, and maintaining the servo head at a desired position in the tape width direction with respect to the servo track, to thus position a data head at a center of a data track.
U.S. Pat. No. 5,689,384, for example, describes a track-following servo system. U.S. Pat. No. 5,689,384 also describes a timing based servo system. The timing based servo system is used together with an LTO (Linear Tape-Open) format, and an example thereof includes an LTO Ultrium (registered trademark) magnetic tape drive available from IBM and a tape cartridge associated therewith.
A linear servo track includes, for example, perceptible transition patterns each constituted of magnetization changes recorded in advance. Those transitions form a timing based servo pattern constituted of a sequence of repetitive circulatory cycles of transitions of two different azimuthal orientations extending in the tape width direction on the linear servo track. For example, the timing based servo pattern includes a transition tilted in a first direction with respect to a direction of the linear servo track, that is, a transition having an azimuthal orientation in the first direction, and a transition tilted in the opposite direction, that is, a transition having an azimuthal orientation in the opposite direction, the two transitions being arranged alternately. Therefore, when a medium moves linearly with respect to a servo read head, a position of the servo read head in the tape width direction with respect to the timing based servo track is detected based on a scale obtained by comparing a time between the two transitions having different azimuthal orientations with a time between two transitions having parallel azimuthal orientations. A relative timing of the transitions read by the servo read head changes linearly in accordance with the position of the head in the tape width direction. Therefore, it is possible to position a plurality of parallel data tracks at different positions in the tape width direction across the servo track (see, for example, U.S. Pat. No. 5,689,384).